• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.2
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• pp.196-203
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• 2017

The renewable energy sources can be thought of one of the major measures to reduce greenhouse gas emissions in the industries. However, the utilization technology for those sources is approaching in the different matters. One of them, thermoelectric generation might be applicable to fishing industry. A various of internal combustion engines are used in a wide range of fisheries. After the ignition process, the heat passed out from the exhaust outlet. Recycling the heat could be not only an energy source but also reduction of green gas emission. Therefore, this study was designed to verify the feasibility of generation from wasted exhaust gas and analyze the performance. The designed experiment devices were connected with a data logger and an electric loader to quantify the currency and voltage. The devices were installed in a coastal fishing vessel for a gillnet fishery. During the whole fishing trips, the amount of generation was measured by engine rpm and the fishing operation procedures including vessel operations. At the maximum 1,500 rpm in the practical range, the generation amount was 113.6 W. The amount difference in relation to connection method was within 5 W: serial connection was 111.4 W and parallel connection was 115.8 W.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.4
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• pp.234-239
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• 2006

This paper introduces an auto-feeding system to exactly control the feeding time and the amount to cultured fishes in aquaculture industrial field. To reduce expensive costs or labors in this field, it was designed by the concept of controlling feed quantity exactly on the basis of fish's feeding behavior pattern in water tank. A feed control method of this system was developed for controlling feed amount by rotor capacity and motor rotated number. Moreover, a scattering section was selected by rotate way of propeller wing to scatter dried feed to designated site, and then, the diameter of its wing was 250mm and maximum scattering distance was 7.6m for 600rpm. Furthermore, the scattering ways were embodied 2 types such as a simplified way and a multistage shift way looks like a manual scattering. As a results, the multistage shift way is more effective to discharge the dried feed widely than the simple way in the water tank.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.3
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• pp.278-286
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• 2017

The age and growth of marbled flounder Pseudopleuronectes yokohamae in coastal waters of the East Sea of Korea off Pohang were determined, by evaluating monthly samples of commercial catches, caught by gill nets and longlines from February 2013 to January 2014. New annuli from annually in P. yokohamae otoliths, and the boundary between the opaque and translucent zones forms from March to May. The relationships between total length (TL) and total weight (TW) were $TW=0.009TL^{3.128}$ ($R^2=0.969$) for females and $TW=0.008TL^{3.150}$ ($R^2=0.964$) for males. The TLs at the time of annulus formation, back-calculated from the otolith-length relationship by reference to the von Bertalanffy growth curves, were $L_t=52.63$ ($1-{\exp}^{(-0.231(t+0.033))}$) for females and $L_t=36.22$ ($1-{\exp}^{(-0.400(t+0.117))}$) for males. Commencing at the age of 3 years, females grew faster than males (P<0.05).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.553-560
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• 2015

The feeding habits of the Pacific bluefin tuna, Thunnus orientalis were examined based on the stomach contents of 330 specimens caught by offshore large purse seine fishery in the southern sea of Korea, 2011. The size of Pacific bluefin tuna used in this study ranged from 34.1 to 67.3 cm in fork length (FL). The percentage of empty stomachs was 41.8%. The main prey items were Pisces and Cephalopoda based on percentage IRI (index of relative importance). The main fish preys were Trachurus japonicus, Bregmaceros japonicus, Engraulis japonicus, and Cephalopoda were Todarodes pacificus, Loligo edulis, Watasenia scintillans. T. orientalis showed ontogenetic change in diet composition. Although Pisces dominated the diet of all length classes the portion of Cephalopoda was relatively higher in size between 40 and 50 cm other than length classes. In terms of seasonal variation in feeding habits, Pisces was the main prey group in all seasons, but Cephalopoda was also frequently consumed during spring and autumn based on %IRI.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.302-311
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• 2015

A series of field tests to estimate the size selectivity of monofilament and multifilament gill net for marbled sole, Pleuronectes yokohamae, were carried out 12 times with five different mesh sizes (86.6, 101.0, 121.2, 137.7 and 151.5mm) in the western sea of Korea from 2007 to 2009. The master selection curve was estimated by the extended Kitahara's method. The total number of catch species was 23 and that of catch was 1,688 in the field tests. Marbled sole of total catch was 1,150 with 68.1 percent. In the monofilament trammel net, the optimum value of total length (TL) per mesh size (m) for 1.0 of retention probability was estimated 0.280 and the values of TL/m were estimated to be 0.187, 0.201, 0.210, 0.218 and 0.226 when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively. In the multifilament trammel net, the optimum value of TL/m for 1.0 of retention probability was estimated 0.307 and the values of TL/m were estimated to be 0.195, 0.211, 0.222, 0.232 and 0.241 when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.1
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• pp.18-26
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• 2011

This study is to contribute to income growth of fishermen by the common octopus fishery characterized in the Tando Bay on the southwest coast of Korea. This area is engaged in Longline fishing (301 persons), Shovel fishing (196 persons), Trap fishing (14 persons) and Torch light fishing (40 persons) in 2008. Population who is joined in the spring becomes main fishery target population of longline fishery in the fall because entering fishing ground in August, and is joined in the fall becomes main fishery target population of longline fishery in the spring because entering fishing ground in December. Average size of common octopus examined by longline 6.26cm, 5.82cm for Shovel fishing, 8.09cm for trap, and expressed big difference by fishery. It needs necessary various kinds of Octopus resource management actions and methods in continuous use. Specially, Fishing force increased by fishing automation system, so the reduction of fishing force is needed to increased by fishing force. Government support and fishermen's self-conscious of resource management is needed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.367-375
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• 2016

Marbled flounder Pseudopleuronectes yokohamae is a commercially important flatfish in the coastal waters of the East Sea off Pohang, Korea. Maturity and spawning dynamics of P. yokohamae were investigated based on samples collected by gill net and long line in the coastal waters off Pohang from January 2013 to December 2014. We analyzed monthly changes in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity, and total length at 50% group maturity. We found that the spawning period was December to February, wherein fecundity ranged from 55,760 eggs at 20.40 cm total length (TL) to 1,559,007 eggs at 46.6 cm TL. The relationship between TL and fecundity (F) was F = 0.0017 TL^3.5604 (R² = 0.6984), and F increased with increasing TL. We estimated the TL at 50% group maturity as 27.4 cm for female and 23.5 cm for male P. yokohamae, respectively. The results from this research will aid in the development of policies on season and minimum catch length for sustainable production of P. yokohamae. We propose that it is necessary to conduct long-term ecological monitoring for this species because biological properties such as spawning ecology and growth performance are being affected by climate change.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.259-266
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• 2011

To produce cupped oyster sprat consistently, we investigated the efficiency of nine settlement substrates using selective breeding of Pacific oyster Crassostrea gigas, with the goal of popularizing off-bottom culture on the west coast of Korea. We also compared the growth and survival of selectively bred sprat (diploid) with triploid sprat from an off-bottom culture system. Considering, the attachment rate and detachment efficiency, producing cupped oyster in a polypropylene gunny bag proved to be the most effective method. There were no differences in shell growth or total weight between the diploids from selective breeding and triploids from off-bottom culture for 5 months. However, the survival rate was 8 times higher in the diploids than the triploids. Transplanting sprat from selective breeding is one way to restore oyster farms and nurture off-bottom culture along the west coast.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.635-641
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• 2016

The feeding habits of juvenile and young Seriola quinqueradiata, which were collected by a hand net and set net in coastal waters of the South Sea during the period from June to August 2014 and 2015, were analyzed. The size range of juveniles was 4.9-10.9 cm FL, and that of young S. quinqueradiata was 11.0-20.4 cm FL. Important prey items in the diets of juveniles were euphausiacea and copepoda, dominated by the Euphausia sp., Paracalanus sp. and Calanus sinicus while the diets of the young consisted mainly of pisces, dominated by Engraulis japonicus, Trachurus japonicus. Stomach content compositions differed significantly among body size levels in both the juveniles and young (ANOSIM, P<0.05). With increasing size, the mN/ST constantly decreased while the mW/ST constantly increased (one-way ANOVA). Graphical analysis of the diet composition showed that juvenile S. quinqueradiata are generalized feeders, young is a specialized feeders characterized by strong individual feeding specialization.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.669-674
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• 2017

Paralytic shellfish toxins (PSTs) are produced by marine dinoflagellate phytoplankton Alexandrium spp. and Gymnodinium spp. These toxins accumulate in filter feeding organisms such as bivalves and the ingestion of contaminated shellfish can cause illness in humans. The mouse bioassay (MBA) has been the preferred PST testing method worldwide for more than 50 years. However, this assay has several disadvantages, such as detection limits, non-toxic-profiles, and the ethical issues of using animals. The aim of this study was to establish an alternative to the MBA method for testing for PSTs. We optimized the analysis conditions of a post-column oxidation-high performance liquid chromatography (PCOX-HPLC) method and the Scotia Rapid Test Kit, and then compared the accuracy of these methods to the MBA method. The results demonstrated a strong correlation between the PCOX-HPLC method and the MBA, although the PCOX-HPLC method required expensive equipment and standard material, and was time consuming. The Scotia Rapid Test Kit promises to be a useful tool, as it provided rapid and qualitative results, although the method sometimes gave a false positive result that could not be explained by toxin profiles.